The invention set forth in this document pertains to new and improved concrete barriers which are intended to be primarily useful in forming vertically extending holes in concrete slabs or similar structures.
Virtually everyone knows that concrete slabs or related structures are usually formed by casting or spreading a "wet" concrete mixture usually containing a hydraulic cement, aggregate and water onto a horizontally extending surface upon which the slab of the concrete is to be located, "working" or "finishing" the wet mixture so as to remove pockets of entrained air and obtain a desired surface configuration and then allowing the wet mixture to harden or "set" so as to form the final slab or other sturcture. Complications have often been encountered whenever it has been necessary or desirable to locate holes extending through such slabs or other structures.
In the past, and even to some degree currently, such holes have been created by workers erecting barricades on a surface out of any conveniently available material at a job site prior to the casting or location of the "wet" concrete mixture on the surface so as to hold back the wet mixture from the locations where holes are desired. This type of procedure is considered disadvantageous for any one or more of a series of different reasons.
Frequently an undesired amount of time is required to locate the materials to construct such barricades and to erect them. On occasion the construction of such barricades has not been effective to adequately hold back "wet concrete" from an area where a hole is desired. Also, the holes created by this type of expedient do not normally have a desired "smooth" or "clean cut" surface configuration.
An understanding of the present invention does not require a more extensive consideration of all of the disadvantages of the this type of "traditional" approach to forming holes in concrete structures. A recognition of the limitations and disadvantages of the creation of holes in a concrete slab or the like by erecting barricades out of any conveniently available material at a job site has resulted in the development of a number of specialized structures for use in creating holes or cavities in concrete slabs or the like in specialized situations.
As an example of this, so called "tub boxes" have been used in forming cavities in solidified concrete in order to accommodate pipes as are used in connecting bathtubs into a complete plumbing system. At least some of such tub boxes have been constructed by molding a polymer which is inert with respect to concrete so as to form a container having areas which can be knocked out of the walls of such boxes so as to accommodate pipes and the like and then installing such boxes in areas where slabs are to be cast from "wet" concrete.
After the concrete has set portions of or covers for such boxes have been removed so as to expose internal cavities or holes of shapes corresponding to the interiors of such boxes. Such cavities or holes may contain small quantities of concrete where the "wet" concrete has flowed around a pipe extending through a hole in such a box but in general have substantially "clean" interiors. Of course, the configuration of concrete shapes or slabs created with other differently constructed barriers will differ dependent upon the nature of the barrier used.
From this latter sentence it will be apparent that a number of different concrete barriers have been developed and used in the past for various specific applications. In spite of this it is considered that there is still a need for new and improved concrete barriers which are relatively inexpensive and which can be easily and conveniently used to create vertically extending holes having desirable interior surfaces through concrete slabs or the like of various different thicknesses. As subsequently indicated this latter is considered important.